Safety paper



Patented May 12, 1931 I r I 1,804,978

parses stares rare-at raise JOHN GENOESE, OF SAN FRANCISCO, CALIFORNIA SAFETY PAPER No Drawing. Application filed March 1, 1926. Serial No. 91,624

l The invention relates to a sensitive paper of sodium thiosulfate, or hypo soda, and for use as negotiable instruments, particuabout ounce of cobaltous nitrate to aplarly checks, which is made to disciose atproximately 2 quarts of water. This secteinpts at alteration of the matter written nd solution may be slightly heated if de- 5 on the paper. I sired to aid in dissolving the cobaltous 55 Sensitive papers for this purpose have nitrate and the sodium thiosulfate and then been largely used by banks and similar inis added to the first solution. The resultstitutions for the purpose of preventing or ant fluid is water white in color and is minimizing check alterations. These senready to be used in treating the paper.

sitive papers have usually comprised a sheet Any appropriate method may be used in 60 of suitable paper coated with a material treating the paper with the fluid, but I prewhich bleaches when an ink eradicatoris fer to immerse the paper in the fluid until applied to the paper, indicating in that all the minute interstices of the paper have manner that an attempt has been made to become filled with the fluid. The paper tamper with the paper or the matter writ-' is then permitted to dry after which it has 65 ten thereon. If thecoating on the paper is the appearance of ordinary paper and is light in color, as it usuallyis to contrast ready for any of the usual operations such withthe inks used for printing and writing as printing or writing thereon. Upon the on the paper, the bleached spot formed application of an ink eradicator to the when the ink eradicator is applied is often safety paper, however, a dark spot is pro- 70 discerned only with difiiculty and is not as duced which immediately gives warning immediately apparent as an indicator of that an attempt has been made to alter th this character should be. In addition, an writing or other matter appearing on the expert check raiser may cover such 'a paper. bleached spot by a deft use of water color. I Claim: In accordance with my invention, I pro- 1. A fluid for use in producing a safety vide a sensitive paper or safety paper which paper comprising the solution formed by produces a dark spot when an ink eradicoinbinlng approximately five ounces of cator is applied thereto, Th d rk ot, alcohol, two quarts of water, a quarter cannot b removed d l -1y indicat ounce of iodine, a quarter ounce of cobal- 80 an attempt at alteration. tous nitrate, and one eighth ounce of sodium It is therefore an object of my-invention thio-sulphate. to provide a safety paper which will cause 2A fluid forms in producing a safety the production of a dark spot when treated paper comprising the solution formed by with an ink eradicator, and in that manner combining. in solution iodine, cobalt nitrate, 5,5 will prevent alteration of the check or other and an alkaline thio-sulphate. instrument, In testimony whereof, I have hereunto In carryin out my invention prepare S t my hand.

JOHN GENOESE.

a fluid material with which the paper in 40 tended to be sensitized is treated. One such fluid with which I have secured good results is prepared by dissolving about ounce of iodine crystals in approximately 5 ounces of alcohol, which may be denatured alcohol. This solution is, dark brown in color and 95 would discolor or color objectionably paper 7 to which it was applied. I therefore add to the first solution of iodine in alcohol a sec- 0nd solution. The second solution is preferably effected by adding about ounce I mm 

